Refrigeration



y 1939- R. R. CANDOR 2,160,470

REFRIGERATI ON Original Filed Sept. 29, 1952 Patented May 30, 1939 UNITED STATES PATENT OFFICE REFRIGERATION Application September 29, 1932, Serial No. 635,389

Renewed April 16, 1937 18 Claims.

This invention relates to refrigeration, and more particularly to refrigerating systems of the character which operate continuously without stopping for temperature adjustments in an object being cooler. Such systems are stopped a relatively few times compared with the stopping operations of the usual intermittently operating refrigerating system which stops for temperature adjustments in the object being cooled. In the continuously operating systems or in those systems whichare designed to operate substantially continuously and stop only for defrosting, repairs or the like, or when the atmospheric temperature drops below the normal range, the penod of idleness is extremely long, so that the refrigerant pressure in the system will become substantially equalized throughout the system. Because of this, these systems need not, and generally are not, provided with special un- 20 loaders for the compressor, and therefore are likely to fail to restart if the attempt is made to restart them relatively soon after they have been stopped. It may occur ,in the operation of these systems that the line current, or source 25 of electrical energy, mayfail for a relatively short period of time, due to-an electrical storm or the like, and it is desirable that the refrigerating system should restart automatically and safely after such a temporary failure of the line 30 current.

It is among the objects of this invention to provide an improved control for the electric motor which drives the refrigerating system which is capable of automatically starting the .3 motor when the current is turned on by the user, which is capable of restarting the system safely if the line current, or source of electrical energy should be turned off temporarily and then be turned on before the refrigerant pres- 40 sure has equalized sufliciently to permit the motor to start. My control is particularly useful in that it insures a relatively long period of rest if the motor should fail to restart on the first attempt, and thus insures that the system has 45 unloaded the compressor before a second attempt to restart.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accomin panying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

Fig. 1 is a diagrammatic representation of a system embodying the features of my invention;

55 and the compressor I0.

Fig. 2 is a diagrammatic representation of a slightly modified system.

A refrigerating system embodying features of this invention is designedto operate continuously during the normal atmospheric temperature range in a dwelling without stopping for cabinet temperature adjustments and is of such a character and capacity, that it automatically maintains proper temperature conditions in the object to be cooled, notwithstanding such continuous operation. Such a system has been more fully described in the copending application, Serial No. 599,239, filed March 16, 1932, to which reference is hereby made for a further disclosure of such a system.

Briefly, such a system includes a compressor lo, a condenser ii, an evaporator l2. The compressor discharges the compressed refrigerant to the condenser II which in turn discharges liquefied refrigerant through the expansion device I3 to the evaporator l2 where the refrigerant is, evaporated and returns through the line H tov The expansion device [3 may be of any suitable character, but preferably is of the elongated orifice type which maintains a fixed, and continuously open orifice, so calibrated as to length and cross-sectional area, that it maintains the evaporator, 12 at the proper temperature to maintain the object being cooled at a substantially constant temperature notwithstanding variations in the surrounding atmosphere. In such a system, the elongated orifice in the expander l3 permits a continuous passage of refrigerant therethrough, and should the compressor lllstop temporarily, this flow through the'orifice continues and in a relatively short time equalizes the pressures throughout the refrigerating system, so that if the compressor should be restarted after such a .short time, it starts with substantially no load. 40

Under ordinary conditions, such a system is stopped only for the purpose of defrosting the evaporator I2 and this defrosting operation is performed only once or twice a month'and is not of the type of stopping operation which is intended to maintain temperature conditions in the object being cooled. On the contrary, such a stopping operation generally permits the object being cooled to warm above the desired temperature, but the operation is performed because of the large accumulation of frost on the evaporator and because of its undesirable inconvenience. After such a stopping operation and because of its long duration, the compressorstarts under no load characteristies and hence a5 motor the starting torque is small. Such a motor compressor unit is capable of starting only-if the entire refrigeration system has become substantially equalized as to pressure throughout, or if the unit is provided with an automatic unloader for removing the pressure differential load during the starting period. In this particular system, no unloader need be used, as it is possible to permit the system to equalize by a sufficiently long period of idleness during the infrequent stops which may be necessary.

A control'is provided for this system which automatically and safely restarts the motor after a temporary line failure, and this control includes means for insuring a relatively long rest period if the motor should fail to start after the first attempt after a line failure. This relatively long period of rest insures that the refrigerant pressures in the refrigerating. system may equalize and thus insure that the next restarting attempt will be made with a much easier pressure differential in the compressor. To this end, the windings of the motor are provided with a control IB which-,maintains the. starting winding energized during a starting period and deenergizes the starting winding at the termination of the starting period. Another control I9 is provided which insures that a relatively long period of rest is provided if the motor should fail to start on the first attempt after a line failure before a second I restarting attempt is made.

The control I8 includes a solenoid 20 which is adapted to close the contact 2| by virtue of the surge current flowing through the main winding I1 during the starting. period; and which is of insufficient strength to hold the contact 2| closed after the motor has attained normal speed. The control I9 includes a thermostatic strip'22 which may or may not be under the influence of the heat of the motor, and which is heated by the resistance 23 which is in series with the line or source of electrical energy'i4 and the motor I5. The thermostatic strip 22 is adapted to open the contact 25 by a snap action against a magnetic resistance 26 when the heater 23 has been overloaded by an abnormal flow of current for a. predetermined period of time such as a period slightly longer than the normal starting period of the motor I5. The strip 22 is provided with an engaging means, or hook, 21 adapted to engage the thermostatic strip 28 and be held in locked position therewith so long as the motor casing 29 is at a temperature near to normal running temperature or at any warmer temperature. Thus, if after a temporary line failure, the control I8 should attempt to start the motor l5, and the motor I5 should fail to start, the resistance 23 will be warmed sufficiently to cause the hook or engaging means 21 to engage the thermostatic strip 23 and be held locked therein so long as the motor casing 29 is near the normal running temportunity to equalize' as to refrigerant pressure motor casing 29 has cooled, this 'manual reset 3| conveniently being in the form of a knob extending from the switch casing (not shown) and being connected to the strip 28 so that it may be manually depressed to release the hook 21. The manual reset 3| is intended to be used by repairmen or the like when they do not wish to wait for the normal cooling period of the motor.

A manual control for stopping and starting the system by the user for defrosting or the like may be provided. Conveniently one of the contacts already provided may be used. Thus a stop 32 maybe provided on the rod 33, which rod may be slidably connected with the strip 22 in such a manner that the contact 25 may be opened without disturbing the strip 22. manually operated, lever construction 34 is provided to engage the hook 35 which forms anextension of the rod 33. Thus the user may operate the lever construction 34 to open the contact 25 without disturbing the strip 22, or may operate the lever construction to permit the contact 25 to be governed by the control I9.

In the modification shown in Fig. 2, a slightly different construction is used so that the electric circuit may be opened if the motor casing becomes overheated. Portions of the system which are designated by the same reference characters, with the suffix a added, which are used in Fig. 1, may be of the same construction and function already described with respect to Fig. 1. The control I9,

however, may be replaced by the control 40 shown in Fig. 2, which control includes the thermostatic to start after a temporary line failure by reason of the overheating of the resistance 42. The strip 4| is provided with engaging means 44 adapted to engage the hook 45 while the motor casing 291:. is at normal temperature "or warmer. The engaging means 44 shown in Fig. 2 is pivoted at 44a to permit the same to pass over the hook 45, but the pivot permits the member 44 to pivot upwardly only and is urged against any pivoting movement below the horizontal position as will be well understood by those skilled in the art. The hook 45 is adapted to be retracted upon the cooling of the casing 29a by reason of a thermostatic strip 46 mounted on the casing 29a which 00- cupies the full line position at normal running temperatures, but occupies the hook retracting position shown in dotted lines when the casing 29a has cooled. A manual control 48 similar to the control is adapted to engage the hook 451 in a manner similar to the engagement of the hook 35.

In addition, the modification shown in Fig. 2 is adapted to provide means for insuring that the system shall not operate when the motor casing 29a has become overheated. To this end the thermostatic strip 46 is adapted to engage the A snap acting,

sleeve 50 which opens the contact II when the motor casing 29a becomes overheated and causes the strip 46 to assume the dotted position 41' to the right of the full line position shown in Fig. 2.

A manual reset 52 may be provided conveniently on the hook 45 to permit a manual reset before the motor has cooled in a manner similar to the reset 3| described with respect to Fig. 1. I

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, said motor having a starting winding and a running winding, a source of electrical energy, means for maintaining the flow of current from said source through said starting winding during a starting period and for stopping the flow of said current at the termination of said starting period, means for rendering said first named means reoperative after a temporary interruption in the supply of electrical energy, and means responsive to the normal operating temperature of a member of said refrigerating system for preventing the flow of current through said windings for a predetermined period of time if said temporary failure should prove to be of insuflicient duration to unload said refrigerating system, and means for equalizing refrigerant pressures in said system during said predetermined period.

' 2. A refrigeratirm' system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, said motor having a starting winding and a running, winding, a source of electrical energy, means for maintaining the flow of current from said source through said starting winding during a starting period and for stopping the fiow of said current at the termination of said period, means for rendering said first named means reoperative after a temporary interruption in the supply of electrical energy, and means responsive to the normal operating temperature of said motor for preventing the flow of current through said windings for a predetermined period of time if said temporary failure should prove to be of insufficient duration to unload said refrigerating system, and means for equalizing refrigerant pressures in said system during said predetermined period.

3. A refrigerating system of the type which runs continuously without stopping for cabinet temperature adjustments in normal household atmospheric temperatures and including a compressor, a condenser and an evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, said motor having a starting winding and a running winding, a source of electrical energy, means for maintaining the flow of current from said source through said starting winding during a starting period and for stopping the flow of said current at the termination of said starting period. means for rendering said first named means reoperative after a temporary interruption in the supply of electrical energy, means responsive to the normal operating temperature of a member of said refrigerating system for preventing the. flow of current through said windings for a predetermined period of time if said temporary interruption should prove to be of. insufiicient duration to unload said refrigerating system, said period of time being longer than said starting period, and means for equalizing refrigerant pressures in said system during said predetermined period.

4. A refrigerating system including a compressor, a condenser and an evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, said motor having a starting winding and a running winding, a source of electrical energy, means for maintaining the flow of current from said source through said starting winding during a starting period and for stopping the flow of said current at the termination of said starting period, means for rendering said first named means reoperative after a temporary interruption in the supply of electrical energy, means responsive to the normal operating temperature of said motor for preventing the flow of current through said windings for a predetermined period of time if said temporary interruption should prove to be of insufficient duration to unload said refrigerating system, said period of time being longer than said starting period, and means for equalizing refrigerant pressures in said system during said predetermined period.

5. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, a source of electrical energy, means for interrupting the supply of current t to the motor upon excessive current passing thereto and for automatically re-initiating operation of the motor thereafter, means brought into operation upon actuation of the first named means after a temporary interruption in the supply of electrical energy for preventing the flow of current to said motor for a predetermined period of time if said temporary interruption should prove to be of insuflicient duration to unload said refrigerating system, and means for equalizing refrigerant pressures in said system during said predetermined period.

6. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, a source of electrical energy, means for interrupting the supply of current to the motor upon excessive current passing thereto and for automatically re-initiating operation of the motor thereafter, means brought into operation upon actuation of the first named means after a temporary interruption in the supply of electrical energy for preventing the flow of current to said motor for a predetermined period of time if said temporary interruption should prove to be of insufiicient duration to unload said refrigerating system, and a continuously open expansion device between said condenser and evaporator for equalizing refrigerant pressures in said system during said predetermined period.

7. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, a source of electrical energy, means for interrupting the supply of current to the motor upon excessive current passing thereto and for automatically re-initiating operation of the motor thereafter, means brought into operation upon actuation of the first named means after a temporary interruption in the supply of electrical energy and responsive to the normal operating temperature of a member of said refrigerating system for preventing the flow of current to said motor for a predetermined period of time if said temporary interruption should prove to be of insufficient duration to unload said refrigerating system, and means for equalizing refrigerant pressures in said system during said predetermined period.

8. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, a source of electrical energy, means for interrupting the supply of current to the motor upon excessive current passing thereto and for automatically re-initiating operation of the motor thereafter, means brought into operation upon actuation of the first named means after a temporary interruption in the supply of electrical energy and responsive to the normal operating temperature of said motor for preventing the flow of current to said motor for a predetermined period of time if said temporary interruption should prove to be of insufficient duration to unload said refrigerating system, and means for equalizing refrigerant pressures in said system during said predetermined period.

9. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, a hermetically sealed casing enclosing said motor and compressor, said compressor being constantly subjected to the pressure difference between the condenser and the evaporator, a source of electrical energy, means for interrupting the supply of current to the motor upon excessive current passing thereto and for automatically re-initiating operation of the motor thereafter, means brought into operation upon actuation of the first named means after a temporary interruption in the supply of electrical energy for preventing the flow of current to said motor for a predetermined period of time, if said temporary interruption should prove to be of insufficient duration to unload said refrigerating. system, and means for equalizing refrigerant pressures in said system during said predetermined period.

10. A refrigerating system including a com-.

pressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving raid compressor, a source of electrical energy, said compressor being constantly subjected to the pressure difference between the condenser and the evaporator, means for slowly equalizing refrigerant pressures upon the inlet and discharge sides of the compressor after the compressor stops, and means for preventing more than one attempt at starting the motor before the pressures have equalized sufficiently to permit the motor to start.

11. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, a source of electrical energy, said system including means for slowly equalizing the refrigerant pressures in said system upon stoppage of the compressor, and means for maintaining the motor deenergized for a period long enough for the pressures to equalize sufficiently for the motor to start after a single attempted start which is unsuccessful because of the pressure difference across the compressor being too great. e

12. A refrigerating system including a compressor, condenser and evaporator in a closed re:

frigerant circuit, an electric motor for driving said compressor, said system being provided with means for equalizing refrigerant pressures upon opposite sides of the compressor when the compressor is idle, a current responsive overload control for said electric motor, and means for delaying the closing of the current responsive overload control to provide an idle period of the compressor sufficient to unload the compressor.

13. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, said system being provided with means for equalizing refrigerant pressures upon opposite sides of the compressor when the compressor is idle, a current responsive overload control for said electric motor, and means responsive to the temperature of said electric motor for controlling the closing of said current responsive control.

14. A refrigerating system including a compressor, condenser and evaporator in a closed refrigerant circuit, an electric motor for drivin said compressor, said system being provided with means for equalizing refrigerant pressures upon opposite sides of the compressor when the compressor is idle, a current responsive overload control for said electric motor, and means responsive to the temperature of a portion of said refrigerant circuit for controlling the closing of said current responsive control.

15. A refrigerating system including a compressor, a condenser and an evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, an overload control for deenergizing the motor during overload and thereafter energizing said electric motor, latch means for preventing the closing of said overload control, and thermostatic means for unlatching said latch means to release the overload control.

16. A refrigerating system including a compressor, a condenser and an evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, an overload control responsive to current flow through the electric motor for deenergizing the motor during overloads and thereafter energizing said electric motor, latch means for preventing the closing of said overlatching said latch means to release the overload control. a

17. A refrigerating system including a compressor, a condenser and an evaporator in a closed refrigerant circuit, an electric motor for driving the said compressor, a current overload means responsive to the current supplied to the electric motor for deenergizing the motor during an overload and thereafter energizing said electric motor, and means responsive to a fall in temperature of a portion of said closed refrigerant circuit for controlling the reclosing of said overload control to re-energize the electric motor.

18. A refrigerating system including a compressor, a condenser and an evaporator in a closed refrigerant circuit, an electric motor for driving said compressor, an overload control for deenergizingthe motor during overload and thereafter re-energizing said electric motor, latch means for preventing the closing of said overload control, and means for unlatching said latch means to release the overload control.

ROBERT R. CANDOR. 

